Dynamic magnetic information storage or retrieval – Record copying – Contact transfer
Reexamination Certificate
2006-09-12
2006-09-12
Tzeng, Fred. F. (Department: 2627)
Dynamic magnetic information storage or retrieval
Record copying
Contact transfer
Reexamination Certificate
active
07106531
ABSTRACT:
A contact magnetic transfer (CMT) method for forming a magnetic pattern, such as the servo pattern on a magnetic recording disk, uses a master template with antiferromagnetically-coupled (AF-coupled) magnetic islands. The template is a rigid or flexible substrate with each magnetic island being two ferromagnetic films antiferromagnetically-coupled by an antiferromagnetically-coupling (AFC) film. In the presence of the applied magnetic field the magnetic moments of the two ferromagnetic films are parallel and substantially identical so they generate a magnetic field that cancels the applied field in the region of the slave disk facing the islands. However, when the applied field is removed, any residual magnetization results in the remanent moments in the two ferromagnetic films being oriented antiparallel as a result of the antiferromagnetic exchange coupling across the AFC film. Thus the islands have no net remanent magnetic moment that can affect the servo pattern transferred to the recording disk.
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Bandic Zvonimir Z.
Marinero Ernesto E.
Berthold Thomas R.
Hitachi Global Storage Technologies - Netherlands B.V.
Tzeng Fred. F.
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